US2255995A - Plasticizer - Google Patents

Description

Patented Sept. 16, 1941 PLASTIOIZEB Be: 1. Cosgrove, Toledo, Ohio, minor to llaskon Company, Incorporated, Toledo, Ohio, a corporation of Delaware No Drawing.

Application August 29, 1938,

Serial No. 221,339 2 Claims. (01. coo-'33) The invention relates to a novel carbon compound which is a plasticizer'for formaldehydeurea molding compositions.

Formaldehyde-urea molding compositions ar thermosetting, i. e., when molded under elevated pressure and temperature they first soften and then harden at the molding temperature. A thermoplastic molding composition, in contrast, remains soft until the molded article has cooled. Although an article molded from a thermosetting composition .can be removed from the mold after a relatively short time and while the article'is still hot, an article molded from a thermoplastic composition cannot be removed from the mold until it has cooled, and thus hardened sufficiently so that it does not become blistered or distorted upon release of the pressure. The length of time for which a molding composition must be left in the mold is one of the factors that determines the cost of articles molded from the composition. A composition that must be left in the mold twice as long as another composition requires about twice as much molding equipment for the same volume of production, and hotmolding equipment is expensive.

Although the thermosetting character of formaldehyde-urea molding compositions is highly advantageous, the softening of such compositions that occurs in the mold before setting or hardening takes place is very important. A thermosetin the central portions of relatively thick articles,

such as knobs and handles.

Insuilicient initial fusing results in an unhomogeneous appearance of the finished article,

such as a streaked surface in the case of a col-.

ored article. The surface appearance that is produced by failure of a molding composition to soften before setting is known as "dog skin.

When a molding composition does not soften sufflciently in the mold, bubbles or pockets of gas are frequently trapped, and produce flaws in the and cause rapid deterioration. Formaldehydeurea molding compositions containing no cellulose have not been found satisfactory for commercial use.

To be suitable for use as a plasticizer, a substance should not be so alkaline as to prevent the formaldehyde-urea molding composition from hardening in the mold. Substances that are highly soluble in water cannot be used as plasticizers, because they seriously impair the resistant properties of a formaldehyde-urea resin.

Phenol has been suggested as a plasticizer for formaldehyde-urea molding compositions, but it is unsatisfactory because it imparts an undesirable color and odor to the compositions. Moreover, the color of a formaldehyde-urea composition containing phenol is so unstable that the composition would have to be handled in a refrigerated dark room to prevent the appearance of the molded articles from being spoiled. Toluene sulfonamides have been used for want of better plasticizers, but their plasticizing effect is so slight that they are of little value.

Only substances that are soluble in formaldehyde-urea resin can be used as plasticizers, because insoluble substances bleed out of the resin and thus spoil molded articles in which they are used. The substances that are soluble in formaldehyde-urea resin are very limited in number. Most of such substances seem to have a molecular structure similar to that of the resin; for example, certain urea derivatives are soluble in formaldehyde-urea resin. However, urea derivatives in general do not have a plasticizing eifect upon formaldehyde-urea molding compositions. Urea itself cannot be used as a plasticizer because of its deleterious effect upon the product. The substances that are both soluble in formaldehydeurea resin and capable of appreciably plasticizing a formaldehyde-urea molding composition are extremely rare.

The principal object of the inventionis to provide a novel plasticizer for formaldehyde-urea molding compositions. More specific objects and advantages are apparent from the description, which merely discloses and illustrates the invention and is not intended t impose limitations upon the claims.

The novel plasticizer of the present invention is a compound having a melting point of about 173 C., which can be-prepared by treating triethanolamine with paratoluene sulfonyl chloride.

A formaldehyde-urea molding composition of the usual type, consisting primarily of cellulosic material (40 to 50%) and a formaldehyde-urea reaction product, may be employed.

Example The starting materials for the prepartion of 5 the present plasticizer are p-toluene sulfonyl chloride.

3 and triethanolamine 0H CHz-CHr-N The novel plasticizer may be prepared as fol- CHI-011F011) CHI-CHI-OH 1 lows: Substantially water-free triethanolamine j (125 parts) is added to 265 parts of pyridine. j Paratoluene sulfonyl chloride (159 parts) is then 1 added gradually, with agitation, and the liquid is cooled to remove the heat generated by the re- 1 action. Cooling is then stopped, and the agita- 1 tion is continued until the temperature of the 1 liquid has risen t 20 C. After methanol has been added to cause precipitation, the precipitate 1 isfiltered off, dried, and dissolved in water. A small amount of triethanolamine is added to the 1 water solution, and the plasticizer is recrystal- 1 lized therefrom. It has a melting point of about 1 173 0.

Four parts of thissubstance may then be f ground in a ball mill, together with parts of i alpha-cellulose fiber impregnated with parts 1 of a formaldehyde-urea reaction product. The 35 j customary modifiers, such as lubricants, accelerators, and coloring matter, may also be added to 1 the ball mill. After an intimate mixture has been 1 obtained in the form of a fine powder, it may be granulated or formed into pellets so that it can 40 3 be used conveniently for charging molds. The

moldingis performed under a suitable pressure at a temperature of about 150 C.

Various applications of the invention may be devised to meet various requirements.

Having described my invention, I claim:

1. A composition comprising a thermosetting formaldehyde-urea reaction product and a plasticizer which has a melting point of about 173 C. and which is substantially identical with the substance obtained by adding parts of substantially water-free triethanolamine to 265 parts of pyridine, then adding 159 parts of paratoluene sulfonyl chloride gradually with agitation, cooling the liquid to remove the heat generated by the reaction, then stopping the cooling and continuing the agitation until the temperature of tl 1e liquid has risen to 20 (3., followed by addition of methanol to cause precipitation, filtering oil and drying the precipitate, dissolving it in water, adding a small amount of triethanolamine to the water solution, and crystallizing said substance from the solution.

2. A composition comprising a thermosetting formaldehyde-urea reaction product, cellulosic material and about 5 per cent of a plasticizer which has a melting point of about 173 C. and which is substantially identical with the substance obtained by adding 125 parts of substantially water-free triethanolamine to 265 parts of pyridine, then adding 159 parts of paratoluene sulfonyl chloride gradually with agitation, cooling the liquid to remove the heat generated by the reaction, then stopping the cooling and continuing the agitation until the temperature of the liquid has risen to 20 0., followed by addition of methanol to cause precipitation, filtering il and drying the precipitate, dissolving it in water, adding a small amount of triethanolamine to the water solution, and crystallizing said substance from the solution.

REX P. COSGROVE.